Response surface methodology and artificial neural network modelling for the performance evaluation of pilot-scale hybrid nanofiltration (NF) & reverse osmosis (RO) membrane system for the treatment of brackish ground water.

Artificial neural network (ANN) and response surface methodology (RSM) were employed to develop models for process optimisation of pilot scale nanofiltration (NF) and reverse osmosis (RO) membrane filtration system for the treatment of brackish groundwater. The process variables for this study were feed concentration, temperature, pH and pressure. The performance of NF/RO was assessed in terms of permeate flux, water recovery, salt rejection and specific energy consumption, which were considered as responses. The experimental design was employed to develop both RSM and ANN models. RSM model was validated for the whole range of experimental levels, while the ANN model was considered for the whole range of experimental design. RSM and ANN models were statistically analysed using analysis of variance (ANOVA). Further, the models were graphically compared for its predictive capacity. Numerical optimisation of NF and RO pilot plant to determine the optimum conditions were verified. Finally, using the optimum conditions, three hybrid configurations of NF and RO were studied to determine the best mode for the treatment of brackish groundwater. It was found that parallel NF-RO had a recovery of 57.18% and rejection of 44.89%, for RO-concentrate-NF (RO-C-NF) recovery was 49.55% and rejection of 38.64% & for NF-concentrate-RO (NF-C-RO), the recovery of 39.53% and rejection of 49.66% was obtained. Results obtained also suggested that the mode of configurations and the feed concentration affect the performance of the hybrid system.

Primary amoebic meningoencephalitis due to Naegleria fowleri.

Primary amoebic meningoencephalitis (PAM) due to Naegleria fowleri was detected in a 36-year-old, Indian countryman who had a history of taking bath in the village pond. He was admitted in a semi comatosed condition with severe frontal headache, neck stiffness, intermittent fever, nausea, vomiting, left hemiparesis and seizures. Computerized tomography (CT) scan of brain showed a soft tissue non-enhancing mass with erosion of sphenoid sinus. However CSF findings showed no fungal or bacterial pathogen. Trophozoites of Naegleria fowleri were detected in the direct microscopic examination of CSF and these were grown in culture on non-nutrient agar. The patient was put on amphotericin-B, rifampicin and ceftazidime but his condition deteriorated and was taken home by his relatives in a moribund condition against medical advice and subsequently died. A literature review of 7 previous reports of PAM in India is also presented. Four of theses eight cases were non lethal. The mean age was 13.06 years with male: female ratio of 7:1. History of contact with water was present in four cases. Trophozoites could be identified in all 8 cases in this series.

Comparative evaluation of surface swab and quantitative full thickness wound biopsy culture in burn patients.

A total of 100 cases of burn were examined and screened bacteriologically for evidence of infection by surface swab culture, quantitative full thickness punch biopsy culture and blood culture. Gram negative organisms predominates the gram positive ones. Surface swab was found to correlate well with the biopsy as far the identification of causative organism is concerned. However, the latter technique was found to be more valuable as it also gives the critical load (>10(5)CFU/g of tissue) of the organism beyond which metastatic invasion of the organism takes place (p<0.01), thus obviating the repeated need for blood culture in burn patients.

A study of prevalence of Chlamydia trachomatis infection in women with first trimester pregnancy losses.

The study included 125 patients in the first trimester of pregnancy, who were divided into group A (50 control subjects with normal intrauterine pregnancy), Group B (50 patients with spontaneous abortion), group C (25 patients with ectopic pregnancy). All the patients were investigated including routine blood and urine tests and special tests related to the cause of pregnancy loss. The patients were tested for IgG antibodies to Chlamydia trachomatis by ELISA technique and conjunctival smear were tested for presence of inclusion bodies to C. trachomatis. It was concluded that C. trachomatis is one of the important cause of spontaneous abortion and ectopic pregnancy. It is highly prevalent in our population, the prevalence being 10% in group A, 26% in group B, 28% in group C. Conjunctival smear showed presence of inclusion bodies in 0.8% patients. With abortions then risk of lower genital tract chlamydia infection spreading to upper genital tract increases. ELISA for C. trachomatis should be done when women are being investigated for the cause of spontaneous abortion and ectopic pregnancy.

Evaluation of minimum inhibitory concentration of quinolones and third generation cephalosporins to Salmonella typhi isolates.

A total of 323 Salmonella typhi isolates (261 isolates obtained during 1995-99 from Ludhiana and 62 randomly selected isolates obtained between 1980-99 from Chandigarh) were analyzed for drug resistant pattern. S. typhi isolates prior to 1986 were sensitive to all the antimicrobials tested by disc diffusion method. Most common multidrug resistance pattern noticed was ACCo T i.e. resistance to ampicillin, Chloramphenicol, cotrimoxazole and tetracycline. This study has revealed that withdrawal of chloramphenicol due to high level of resistance during 1990-94, has led to re-emergence of 43-93 percent chloramphenicol sensitive mutants during 1995-99. Two S. typhi isolates in 1995 and one in 1999 from Ludhiana depicted resistance to ciprofloxacin. Susceptibility of S. typhi isolates to third generation cephalosporins ranged between 87 to 100 per cent. There was a gradual increase with time period in mean minimum inhibitory concentration (MIC) of ciprofloxacin as it increased from 0.066 ug/ml for 1980-83 S. typhi isolates to 0.13 ug/ml for the 1996-99 isolates. Similarly, cefotaxime mean MIC for 1980-83 isolate was 0.172 ug/ml which further increased up to 0.32 ug/ml for S. typhi isolates encountered between 1996-99. In contrast, mean MIC value of 0.62 ug/ml of Ceftriaxone remained unchanged irrespective of the year of isolation of S. typhi isolates.